1. Field of the Invention
The present invention relates to an endoscope using light emitting devices, serving as an illumination optical system, and an endoscope to which an adapter using light emitting devices serving as an illumination optical system is attachable.
2. Description of the Related Art
Endoscopes are widely used in the medical and industrial fields. Objects to be inspected using endoscopes are in living bodies and plants. Therefore, each endoscope requires a light source for illuminating an observation object.
General endoscope apparatuses each provide a light source, serving as an external device for an endoscope. Illumination rays emitted from the light source are supplied to a light guide disposed in the endoscope. The supplied illumination rays are transmitted through the light guide and are then emitted from an illumination window arranged at the distal end of an insertion unit, thus illuminating an observation area.
A recently proposed endoscope has an LED illumination system at the distal end of its insertion unit instead of the combination of a light source for illuminating an observation area and a light guide fiber. According to this endoscope, an observation area is directly illuminated by light emitted from the LED illumination system. In addition, the endoscope captures, using a solid-state image pickup device, an image of an observation area illuminated by light emitted from the LED illumination system. The above-described technique realizes a high functional endoscope having a small-diameter insertion unit and a simple structure.
Japanese Unexamined Patent Application Publication No. 2002-51971 discloses an endoscope in which the amount of illumination rays of an LED illumination system is increased, the system being arranged at the distal end of an insertion unit.
According to a known technique, to observe an observation area illuminated by illumination rays or the like using an endoscope, an adapter for changing optical characteristics, such as the direction of view and the angle of view, depending on the purpose of observation, is attached to the distal end of an insertion unit of the endoscope. In other words, a distal-end adapter is attached to the distal end of the insertion unit, thus achieving various observations using one endoscope. Therefore, when the above-described LED illumination system is arranged to the adapter, the usability of the endoscope can be improved.